In economics, what market structure has many sellers offering identical products with free entry and exit?

In economics, a market structure with many sellers offering identical products and free entry and exit is perfect competition.

The model assumes many buyers and sellers, so no individual participant can control the market price. Each firm is therefore a price taker: it accepts the price determined by overall supply and demand. Because products are identical, buyers have no reason to prefer one seller over another based on the product itself.

Perfect competition also assumes that buyers and sellers have complete information and that firms can enter or leave the industry without major obstacles. In the long run, entry tends to reduce unusually high profits, while exit reduces losses. Firms typically produce where price equals marginal cost, an outcome associated with allocative efficiency.

Few real-world markets satisfy every assumption exactly. Agricultural markets are sometimes used as approximate examples, although products, information, transport costs, and government rules can prevent a perfect match. Perfect competition is mainly a benchmark for comparing real market structures such as monopoly and oligopoly.